This invention relates to a semiconductor memory device, and more particularly to a data read/write portion of a dynamic memory device.
In general, a semiconductor memory device consists basically of a row circuit for driving word lines, a column circuit for driving bit lines and for executing writing or reading operations, and a number of memory cells connected between the word lines and the bit lines, for storing information therein. The present invention mainly relates to the column circuit, which is, in other words, a data read/write portion of the semiconductor memory device.
On one chip of the memory device, there are various pins such as those for receiving power supply voltages, for receiving clocks, for receiving address signals, and for data input and data output. It is an essential problem for a large scale integrated circuit to decrease the number of pins.
There is known a memory device in which data-input pins and data-output pins are commonly used having a decreased number of pins. Such an I/O pin common system has been realized in a static memory. However, in a dynamic memory, such an I/O pin common system has not yet been realized without employing a static circuit. When the static circuit is included in the dynamic memory, a large amount of power is consumed by the static circuit so that the superior feature of low power consumption in the dynamic memory device is deteriorated.